--- a.c	2018-04-21 14:14:59.246666844 +0300
+++ b.c	2018-04-21 14:16:11.146666867 +0300
@@ -57,11 +57,12 @@
             fds[mode] = open(argv[mode + 1], O_RDONLY);
         }
         if (fds[mode] == -2) {
+            mode = -1;
             continue;
         }
         u8 buf[16];
         isize rd = read(fds[mode], &buf, 16);
-        if (rd == -1) {
+        if (rd <= 0) {
             fds[mode] = -2;
             mode = -1;
             continue;